MIT Robotic Fish Is Self-Contained, Autonomous, Fast

A robotic fish created by grad student Andrew Marchese at MIT's Distributed Robotics Laboratory is described as the first self-contained autonomous soft robot that is capable of rapid body motion. No more languorous sinuosity (as much as we enjoy it) - this fish is too quick to catch!

The robotic fish was built by Andrew Marchese, a graduate student in MIT’s Department of Electrical Engineering and Computer Science and lead author on the new paper, where he’s joined by Rus and postdoc Cagdas D. Onal. Each side of the fish’s tail is bored through with a long, tightly undulating channel. Carbon dioxide released from a canister in the fish’s abdomen causes the channel to inflate, bending the tail in the opposite direction.

Each half of the fish tail has just two control parameters: the diameter of the nozzle that releases gas into the channel and the amount of time it’s left open. In experiments, Marchese found that the angle at which the fish changes direction — which can be as extreme as 100 degrees — is almost entirely determined by the duration of inflation, while its speed is almost entirely determined by the nozzle diameter. That “decoupling” of the two parameters, he says, is something that biologists had observed in real fish.

“To be honest, that’s not something I designed for,” Marchese says. “I designed for it to look like a fish, but we got the same inherent parameter decoupling that real fish have.”

The fish can perform 20 or 30 escape maneuvers, depending on their velocity and angle, before it exhausts its carbon dioxide canister. But the comparatively simple maneuver of swimming back and forth across a tank drains the canister quickly. “The fish was designed to explore performance capabilities, not long-term operation,” Marchese says. “Next steps for future research are taking that system and building something that’s compromised on performance a little bit but increases longevity.”